A triple-band multi-input multi-output (MIMO) antenna is presented.The proposed antenna consists of a C-shaped monopole antenna that provides dual-band resonant antenna. By protruding an L-shaped parasitic strip on the ground plane, a... more
A triple-band multi-input multi-output (MIMO) antenna is presented.The proposed antenna consists of a C-shaped monopole antenna that provides dual-band resonant antenna. By protruding an L-shaped parasitic strip on the ground plane, a third band as well as enhancement of the isolation between two ports in MIMO array is achieved. The proposed antenna can cover 2.1–2.6, 3.3–4, and 5.4–6 GHz, which are allocated for WLAN and WiMAX applications. The proposed triple-band antenna structure is used in different two-element MIMO arrays. Simulation results show that the S11, S12, and S22 of the MIMO arrays are independent of the position of the two-element. The results show good S-parameters, high peak gain and radiation efficiency, and stable radiation patterns among the triple-band coverage. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1321–1325, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26799
Research Interests: Antennas, Multiple-input Multiple-output (MIMO) Systems, MIMO communication, Wimax, Antenna, and 11 moreOptical physics, WLANs, Multiband antenna, MIMO antenna, Electrical And Electronic Engineering, MIMO Antennas, Multiband, monopole antenna, Printed Monopole Antenna, Compact Printed Monopole Antenna, and Triple band
In this paper, the design, simulation, and fabrication of a double-ridged antenna is presented. The designed double-ridged antenna is most suitable as a feed element in reflectors of the radar systems and EMC applications. The designed... more
In this paper, the design, simulation, and fabrication of a double-ridged antenna is presented. The designed double-ridged antenna is most suitable as a feed element in reflectors of the radar systems and EMC applications. The designed antenna has a voltage standing wave ratio (VSWR) less than 2 for the frequency range of 8–18GHz. Moreover, the proposed antenna exhibits satisfactory far-field radiation characteristics in the entire operating bandwidth. A coaxial line to rectangular double-ridged waveguide transition is introduced for coaxial feeding of the designed antenna. The proposed antenna is simulated with commercially available packages such as CST microwave studio and Ansoft HFSS in the operating frequency range. Simulation results for the VSWR, radiation patterns, and gain of the designed antenna over the frequency band 8–18GHz are presented and discussed.
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A substrate-integrated waveguide (SIW) H-plane sectoral horn antenna, with significantly improved bandwidth, is presented. A tapered ridge, consists of a simple arrangement of vias on the side flared wall within the multilayer substrate,... more
A substrate-integrated waveguide (SIW) H-plane sectoral horn antenna, with significantly improved bandwidth, is presented. A tapered ridge, consists of a simple arrangement of vias on the side flared wall within the multilayer substrate, is introduced to enlarge the operational bandwidth. A simple feed configuration is suggested to provide the propagating wave for the antenna structure. The proposed antenna is simulated by two well-known full wave packages, the Ansoft HFSS and the CST microwave studio. Close agreement between both simulation results is obtained. The designed antenna shows good radiation characteristics and low VSWR, lower than 2.5, for the whole frequency range of 18– 40 GHz.
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In this article, a synthesis procedure is proposed to achieve a flat-topped radiation pattern in optical leaky-wave antennas (OLWAs). In the proposed procedure, the antenna is divided into sections, each with an appropriate phase... more
In this article, a synthesis procedure is proposed to achieve a flat-topped radiation pattern in optical leaky-wave antennas (OLWAs). In the proposed procedure, the antenna is divided into sections, each with an appropriate phase constant, length and leakage constant. By determining a proper value for these parameters, the desired flat-topped pattern is achieved. The phase constant of the sections is obtained such that their beam pointing angle follows an appropriate layout in the region of interest. Further, by introducing the same beamwidth and the same radiation power for the radiating sections, the two latter parameters, i.e., the length and the leakage constant of the sections are determined. The proposed synthesis procedure is applied to a conventional OLWA, i.e., grating waveguide (GWG), to achieve a flat-topped pattern in the angular region of -30°to -11°. Results show that the desired radiation pattern is well synthesized. Finally, the effects of beam spacing and the sectio...
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A novel compact four element multiple input multiple output (MIMO) antenna is proposed. The antenna is composed of four E-shaped patch elements and operates at 5.8 GHz. The single Eshaped patch antenna, operate at this frequency is... more
A novel compact four element multiple input multiple output (MIMO) antenna is proposed. The antenna is composed of four E-shaped patch elements and operates at 5.8 GHz. The single Eshaped patch antenna, operate at this frequency is designed using the Invasive Weed optimization algorithm. This algorithm is then applied to design the selected orthogonal polarization arrangement for two and four element MIMO antenna for high degree of isolation. In order to measure the array performance under MIMO signaling conditions a multi-port metric is used to characterize the compact array rather than the scattering matrix characterization. The designed antennas have low profile, easy fabrication, low cost and good isolation. The simulation and measurement results of reflection coefficient, mutual coupling and radiation pattern are presented.
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This paper presents a novel method to enhance the pattern characteristics of the TEM horn antenna for 2–14 GHz frequency band. The conventional TEM horn antenna introduces some fluctuations in the main lobe radiation pattern over the... more
This paper presents a novel method to enhance the pattern characteristics of the TEM horn antenna for 2–14 GHz frequency band. The conventional TEM horn antenna introduces some fluctuations in the main lobe radiation pattern over the higher frequencies, i.e., 10– 14 GHz. This motivated us to propose a new method to remove the aforementioned impact by carving an arc shape to the open end of exponentially tapered plates. The associated curvature of this arc is optimized to completely remove the fluctuation. The measurement results show that the improved TEM horn antenna structure exhibits low VSWR as well as radiation pattern over 2–14 GHz frequency band.
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A simple design procedure for a double ridge waveguide low-pass filter (LPF) is proposed in this article. The procedure follows similar steps involved in a stepped impedance microstrip LPF. The starting point is calculating lumped element... more
A simple design procedure for a double ridge waveguide low-pass filter (LPF) is proposed in this article. The procedure follows similar steps involved in a stepped impedance microstrip LPF. The starting point is calculating lumped element low-pass prototypes and converting them to the double ridge waveguide sections. Step discontinuities are also studied and a lumped element model is proposed by comparing S parameters calculated by HFSS software. The results are then applied to design a six order maximally flat double ridge LPF with 4 GHz cutoff frequency. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:120–124, 2014
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Superconducting microwave circuits are composed of components made from superconducting microstrip transmission lines (SMTLs). The spatial features of the superconductors provide the system operation at high speed and low noise floor.... more
Superconducting microwave circuits are composed of components made from superconducting microstrip transmission lines (SMTLs). The spatial features of the superconductors provide the system operation at high speed and low noise floor. However, coupling the external electromagnetic field in these systems reduces or nullifies their performance. This article presents a general solution for evaluating the electromagnetic behavior of multiconductor SMTLs under plane wave excitation. The analysis is portrayed in the spectral domain. Using the proposed approach, the electromagnetic susceptibility of the lines is evaluated for two proximity SMTLs. It is then investigated in different scenarios where the effect of film thickness, film spacing, and operating temperature is investigated. The study reveals that by increasing the film thickness or film spacing or decreasing the operating temperature, the lines’ susceptibility is increased. Further, it is shown that for small film spacing, the su...
The parabolic equation method gives accurate results in calculation of scattering from objects with dimensions ranging from one to tens of wavelengths. Solving parabolic equation with the marching method needs limited computer storage... more
The parabolic equation method gives accurate results in calculation of scattering from objects with dimensions ranging from one to tens of wavelengths. Solving parabolic equation with the marching method needs limited computer storage even for scattering calculations of large targets. In order to compute monostatic RCS, backward scattered field is required. Parabolic equation separates forward and backward scattered fields. In this paper, first the calculation procedure of monostatic radar cross section using parabolic equation in three dimension is studied and the necessary equations are derived. Backward scattered fields in three dimension are calculated by developing two dimensional method. Monostatic RCS of a reflector antenna has been computed by using a staircase model in the parabolic equation. The results are compared with physical optics results.
Designing superconducting microwave planar components cannot be well performed without utilizing a full-wave simulator. However, well-known conventional simulators, i.e., Ansoft HFSS or CST microwave studio, cannot predict the... more
Designing superconducting microwave planar components cannot be well performed without utilizing a full-wave simulator. However, well-known conventional simulators, i.e., Ansoft HFSS or CST microwave studio, cannot predict the electromagnetic behavior of superconducting circuits. Therefore, this paper proposes a simulation model through utilizing which one can evaluate superconducting microwave components in conventional simulators. The model works for a film thickness up to 5 λ and can be used up to millimeter-wave frequencies. The proposed model replaces the superconducting film by a sheet with appropriate impedance. The value of the equivalent sheet impedance is determined subject to the current distribution within the film. Through the proposed simulation model, the characteristic impedance and phase constant of several superconducting microstrip transmission lines are obtained using Ansoft HFSS. The results are compared with those from theoretical formulas. The agreement betwee...
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Abstract It is well-known that the reduction of side lobes is important for decreasing interference with components in an optical system, as well as obtaining high information security and lowering power losses. This paper introduces a... more
Abstract It is well-known that the reduction of side lobes is important for decreasing interference with components in an optical system, as well as obtaining high information security and lowering power losses. This paper introduces a procedure, based on the simultaneous control of the phase and leakage constants, through which the side-lobe level (SLL) of an optical leaky-wave antenna (OLWA) can be controlled. The synthesis procedure is portrayed using a low SLL conventional OLWA i.e., grating waveguide (GWG). The standard telecommunication wavelength of 1550 nm is considered as the operating wavelength. The simulation results confirm the accuracy of the design procedure. According to the results, the antenna has a low SLL of − 29 dB and a high gain of 26 dBi. The reflection coefficient of the resulting antenna, − 31 dB at the design wavelength, makes the antenna suitable for optical wireless communications.
Research Interests: Optical physics and Optik
Several studies have been conducted on an externally-excited microstrip transmission line; however, no study, to the best knowledge of the researchers, has examined the superconducting microstrip transmission lines (SMTL), which are the... more
Several studies have been conducted on an externally-excited microstrip transmission line; however, no study, to the best knowledge of the researchers, has examined the superconducting microstrip transmission lines (SMTL), which are the main part of the superconducting circuits. This article aims to investigate the radiated susceptibility of SMTL under plane wave excitation. The analysis is based on modeling the superconducting film as a current sheet with specified impedance. It is revealed that the equivalent sheet impedance depends on the current distribution within the film; hence, London's second equation is employed to obtain an integral equation to acquire the current distribution and, subsequently, the equivalent sheet impedance. Then, the susceptibility of the SMTL is calculated after applying the boundary condition at the equivalent impedance surface. The procedure is performed using spectral-domain approach and verified by COMSOL software. Finally, the susceptibility of the SMTL is examined at different temperatures and for different film thicknesses. The results show that the lower temperature makes the SMTL more susceptible to an external electromagnetic field. Moreover, the same behavior is observed for increased film thickness.
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Research Interests: Antennas, Antenna arrays, Antenna, Slotted Waveguide Antenna Array, Leaky-wave Antenna, and 10 moreArray, Substrate Integrated Waveguides, Ridge, Electrical And Electronic Engineering, Array Antenna, Leaky Waves, Ridged Substrate Integrated Waveguide, Periodic Leaky Wave Antenna, Open Stopband Elimination, and Collinear Slotted Antenna
ABSTRACT A novel harmonic-suppressed microstrip stepped impedance lowpass filter (LPF) using Defected Microstrip Structure (DMS) is proposed. In order to cause the spurious passband suppression, appropriate geometries of DMS resonators... more
ABSTRACT A novel harmonic-suppressed microstrip stepped impedance lowpass filter (LPF) using Defected Microstrip Structure (DMS) is proposed. In order to cause the spurious passband suppression, appropriate geometries of DMS resonators have etched in the low impedance sections. Due to the attenuation poles of two kinds of resonators, it is found that harmonic responses are not only suppressed effectively, but a wide stopband can be also obtained. A demonstration filter with cutoff frequency at 2.5 GHz has been designed, fabricated and measured. The proposed filter also exhibits a very wide stopband of 145% (referred to a suppression degree of 20 dB).
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In this paper a neural network based approach, applicable in real time applications, is proposed for detecting the number and location of defective elements in a typical uniformly excited microstrip planar array antenna fed in a serial... more
In this paper a neural network based approach, applicable in real time applications, is proposed for detecting the number and location of defective elements in a typical uniformly excited microstrip planar array antenna fed in a serial manner. Here the defective elements are those elements that are not excited by the feed lines but radiations due to the induced currents
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This paper presents a new shaped reflector antenna for wide beam azimuthal patterns and a cosecant squared elevation pattern. Elliptical strips instead of parabolic strips are used in horizontal planes of the reflector surface to achieve... more
This paper presents a new shaped reflector antenna for wide beam azimuthal patterns and a cosecant squared elevation pattern. Elliptical strips instead of parabolic strips are used in horizontal planes of the reflector surface to achieve this purpose. Simulation and measurement results of the shaped reflector fed by a ridged horn antenna are presented.
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ABSTRACT A new method to design a cosecant squared radiation pattern in a shaped reflector antenna is proposed. Surface of the proposed reflector antenna is expanded by modified Jacobi polynomials. The expansion coefficients are optimized... more
ABSTRACT A new method to design a cosecant squared radiation pattern in a shaped reflector antenna is proposed. Surface of the proposed reflector antenna is expanded by modified Jacobi polynomials. The expansion coefficients are optimized by using particle swarm optimization (PSO) algorithm to achieve desired cosecant squared radiation pattern in elevation plane and a narrow pencil beam radiation pattern in azimuth plane. The antenna is analyzed by physical optics (PO) method.
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ABSTRACT In this article, a dual-antenna structure is presented for UHF RFID tag. The proposed structure is made of two L-shaped strip antennas along with a cross-shaped slot loaded patch. One antenna is exclusively used for receiving and... more
ABSTRACT In this article, a dual-antenna structure is presented for UHF RFID tag. The proposed structure is made of two L-shaped strip antennas along with a cross-shaped slot loaded patch. One antenna is exclusively used for receiving and harvesting full energy with complex conjugate of tag chip, whereas another used as backscatter to enhance maximum differential radar cross section with purely real input impedance, which results in the enhancement of read range. Further, electromagnetic band gap structure is used around the dual-antenna structure to increase the gain which results in improved read range. The proposed antennas are fabricated and the S-parameters are measured with the help of differential probe technique. Simulation and measurement results are found in good agreement. The performance of the proposed antenna is also investigated when it placed on different materials such as metal, wood, glass, and plastic. The study shows that the read range of antenna increases considerably when it is mounted on a metallic surface, while the maximum performance is observed when the antenna is attached on a glass surface with highest relative permittivity. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2015.
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ABSTRACT A novel miniaturized parallel coupled-line bandpass filter with suppression of second, third and fourth harmonic frequencies, is demonstrated in this paper. The new filter is based on the slow-wave effect of the defected ground... more
ABSTRACT A novel miniaturized parallel coupled-line bandpass filter with suppression of second, third and fourth harmonic frequencies, is demonstrated in this paper. The new filter is based on the slow-wave effect of the defected ground structure (DGS) to achieve size minimization, while the spurious responses are eliminated by the band-rejection property. These features offer the classical parallel coupled-line bandpass filter simultaneous compactness and wide stopband performance. Using DGS does not require the filter parameters to be recalculated and, this way, the classical design methodology for coupled-line microstrip filters can still be used. The simulations and measurements of a 2.0 GHz prototype bandpass filter are presented. The measured results agree well with the simulation data. Compared with the conventional parallel coupled-line bandpass filters, the second, third and fourth measured spurious responses are suppressed to -45, -43 and -34 dB, respectively. In addition, the size of the prototype filter circuitry can be reduced up to 20%.
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Research Interests: Antennas, Antenna, Slotted Waveguide Antenna Array, Leaky-wave Antenna, Substrates, and 9 moreSubstrate Integrated Waveguides, Slot Antenna, Electrical And Electronic Engineering, Siw, Antenna measurements, Leaky Waves, Ridged Substrate Integrated Waveguide, Long Slot, and Periodic Leaky Wave Antenna
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A ridged circular patch antenna element excited by a transmission line proximity method is analyzed. The approach is based on conserving the reaction at the ridged position using the cavity model with the assumption of a linear variation... more
A ridged circular patch antenna element excited by a transmission line proximity method is analyzed. The approach is based on conserving the reaction at the ridged position using the cavity model with the assumption of a linear variation of the current distribution on the overlap region of the line and the patch. For a given thickness and patch radius, the smallest line to ground plane spacing for which the radiator is matched to the line is found. Finally, our results are compared with measured data
Research Interests: Antennas, Antenna, Slotted Waveguide Antenna Array, Leaky-wave Antenna, Substrates, and 9 moreSubstrate Integrated Waveguides, Slot Antenna, Electrical And Electronic Engineering, Siw, Antenna measurements, Leaky Waves, Ridged Substrate Integrated Waveguide, Long Slot, and Periodic Leaky Wave Antenna
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ABSTRACT The new reconfigurable antenna array is demonstrated for multiple input multiple output (MIMO) communication systems. The antenna system consists of an array of two printed monopole antenna separated by a distance of 10.2 mm (of... more
ABSTRACT The new reconfigurable antenna array is demonstrated for multiple input multiple output (MIMO) communication systems. The antenna system consists of an array of two printed monopole antenna separated by a distance of 10.2 mm (of the lowest frequency band). Each of the dipoles can be reconfigured in length using PIN diode switches. This has been done by changing the switch state to either on or off mode. With the switch closed, the antenna operated at a lower frequency of 2.3 GHz, and to switch opened, the antenna operated at 3.5 GHz. The preference of reconfigurable antenna is that, the radiation characteristics are certain, since the resonance frequency is changed. Invasive Weed optimization(IWO) algorithm is used for the design and optimization of the single printed monopole antenna, to operate at these frequencies. This algorithm is then applied to design two channel MIMO antenna arrays for high degree of isolation. It is shown that good MIMO performance can be achieved even for small element spacing. The simulation results are presented.